EFFECTS OF HEAT TREATMENT OF SKIM-MILK POWDER AND LEVELS OF FAT AND PROTEIN IN MILK REPLACER DIETS ON THE GROWTH OF CALVES

Abstract

High-temperature-treated skim milk (HTSM) used in milk replacers for calves resulted in no growth response to an increased protein level as compared with low temperature treatment (LTSM), where an increase in protein level from 20.7 to 25.6% of the dry matter resulted in an increase (P < 0.05) in growth rate during the first 19 days on experiment. The HTSM resulted in a greater depression of gross energy intake than the LTSM when dietary fat levels were changed from high to low. Increasing the fat level from 18.0 to 20.9% of the dry matter improved calf health, and rate of gain (independently of energy intake) during early life. The intake of gross energy from high fat diets tended to be higher with the high protein level than with the low protein level. This tendency was reversed in the low fat diets. From 19 days of age to market weight (95 kg liveweight), energy intake increased with increased protein and fat in the diet. During this period, daily gain (after removing the effect of energy intake) responded only to increased protein level in the diet. However, calves fed HTSM had lower (P < 0.05) dressing percent than those fed LTSM.